Improving GQRX integration with Fldigi/Flrig for panadapter operation

[David Ranch]

Hello Everyone,

I have Gqrx working well here with Linux and I've been thinking of a new project.  Specifically, I have a Yaesu FT950 that has an easy to access IF output at 69Mhz and many people have used little RTL dongles as a panadapter.  This works nicely but the frequency display on Gqrx will be wrong as the VFO is changed on the HF radio and there isn't any coordinated rig control.  I'd like to understand if it would be possible to do the following with Gqrx:

   - Feature #1 - Lock the RTL dongle to one frequency (69Mhz) with a configurable offset to avoid the common DC center point
   - Feature #2 - Read the frequency from Flrig and display it in Gqrx so the frequency display is correct - http://www.w1hkj.com/FldigiHelp-3.22/xmlrpc-control.html
   - Feature #3 - If I click on a signal in Gqrx's waterfall, Gqrx will instruct Flrig to QSY the HF radio to the proper frequency + sweet spot (that's +1000hz on the Yaesu FT950)

Would making enhancements be difficult to do?

--David
KI6ZHD

[Alexandru Csete]

Hi David,

What you want is certainly possible to implement. It can become
difficult and time consuming if such functionality has to be
integrated properly with the rest of the application.

During earlier discussions with people I rejected adding this feature
mostly because I didn't want it enough to justify the time it would
take. I said that if I really needed this I would just fork the code
and change it without thinking too much about compatibility with the
existing SDR operations. That could be done quite easily.

Alex

[David Ranch]

Hey Alex,

The issue I see with forking is that then the new application looses the benefit from all the fixes and improvement of the code going into the main project.  Conceptually, the UI isn't changed all that much and maybe the setup of it could be done more as a skin or what not.  I do realize that this would fundamentally change the way Gqrx would work in this mode but I think a ton of people would love this synchronization functionality.

--David

[Alexandru Csete]

I'm not so much worried about UI changes; I'm more worried about
merging two conceptually very different tuning functionalities that go
all the way from the GUI to the hardware.

Maybe I misunderstand the setup, but if you only need the pandapter
functionality in gqrx and not the receiver itself, then 80% of the
gqrx code is irrelevant for this.

Alex

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[David Ranch]

Hey Alex,

To be honest, my first email was to get the *base* functionality going where Gqrx would control the overall system and influence rig control to move to a specific area of the "wider" IF range.  If we were to stop there, yes, I agree that  using Gqrx would be overkill.  Why I wanted to use Gqrx was that the next idea would be that once someone would click on a signal on the wide panadapter, GQRX would instruct the rig control system to QSY the radio to put that frequency in the rig's sweet  spot.  The next step would then be more advanced but to actually have Gqrx do the SSB demodulation and feed that audio it into Fldigi directly where it could do the various digital decoding.  With a setup like this, we get all the benefits of the SDR, it's filtering, etc.   The one thing I'm not 100% sure is how TX would be handled but if the HF signal is properly centered in the rig's sweet spot, standard FLdigi audio TX into the radio itself should work.

--David

[Geoff McAlpin (NM7V)]

I would love to see this implemented into gqrx as the application is a native Linux program and I would like to have a good panadapter for my IC-706MK2G which doesn't have the best filtering. There are ways to do the same with HPSDR but since it's not a Linux application I'm reluctant to do so.

[Zilvis (LY2SS)]

2015 m. sausis 3 d., šeštadienis 23:51:54 UTC+2, Geoff McAlpin (NM7V) rašė:

I would love to see this implemented into gqrx as the application is a native Linux program and I would like to have a good panadapter for my IC-706MK2G which doesn't have the best filtering. There are ways to do the same with HPSDR but since it's not a Linux application I'm reluctant to do so.

So do I.

For adventerous souls. I have FT857 and excellent receiver funcube  pro+. One should have capability to recompile gqrx (pybombs).
I added these two lines to remote_control.cpp in RemoteControl::setNewFrequency  right below rc_freq = freq; line:

QProcess rigas;

rigas.startDetached("rigctl", QStringList() << "-m 2" << "F" << QString::number(freq));

(you need running rigctld attached to your rig for queries to be accepted)

I am not programmer but this thing works smooth - all the clicked stations are tuned on my FT-857 - really nice feeling. I guess this should work with RTL dongles with upconverters and various hamlib supported tranceivers.

Now I need to make dongle protection relay box with some cabling.

Best 73! Zilvis LY2SS

THANK You all involved in beautiful gqrx software!


p.s. pybombs was the only way to put latest gqrx-dev into my 12.04 Ubuntu LTS, because proprietary video (Intel/PowerVR) in my netbook is not supported in later versions.

[Geoff McAlpin (NM7V)]

Thanks, Zilfis, I'll give this a try.